Centrifugal pump with gas separation means



Oct. 26, 1965 H. E. ADAMS CENTRIFUGAL PUMP WITH GAS SEPARATION MEANS 3Sheets-Sheet 1 Filed Feb. 2 1962 R. mm u m4 5 0 B00 2 4 2 4 m J 0 W AI fM o0 m: w /l AV RY I BY WMM/j 70%, 7M

TTOF/VEYS Oct. 26, 1965 H. E. ADAMS 3,213,794

CENTRIFUGAL PUMP WITH GAS SEPARATION MEANS Filed Feb. 2, 1962 3Sheets-Sheet 2 BY 77h12@ 7%@ f 7f3@ ATTORNEYS Oct. 26, 1965 H. E. ADAMS3,213,794

CENTRIFUGAL PUMP WITH GAS SEPARATION MEANS Filed Feb. 2, 1962 5Sheets-Sheet 5 lNvENToR /fmcup E. ,40g/ws ATTORNEYS United States PatentO 3,213,794 CENTRFUGAL PUMP WETH GAS SEPARATION MEANS Harold E. Adams,South Norwalk, Conn., assigner to The Nash Engineering Company, acorporation of Connecticut Fiied Feb. 2, 1962, Ser. No. 170,673 7Claims. (Cl. 103-5) This invention relates to improvements in pumps ingeneral, and in particular to an improved vapor and liquid separatingstructure for a pump having the capacity to pump fluids in all phases,whether they be in the liquid, gas or vapor state.

In particular, the present invention is concerned with improvements inpumps of the type shown generally in my prior U.S. Patent No. 2,940,657issued lune 14, 1960. Pumps of this type employ a liquid ring vaporcompression portion in series combination with a centrifugal liquidimpeller portion, and are capable of pumping a mixed phase iiuid anddelivering the fluid into two separate discharges, one liquid and theother gas or vapor, each portion to a desired higher pressure.

In my aforementioned prior art patent the separation of the gases andnon-condensable vapors from the liquid portion occurred on the dischargeside of the liquid impeller. Accordingly, when pumping a mixture ofliquid and gases, the second stage impeller contributes very little tothe overall pressure development of this pump, because of the inabilityof the impeller portion to produce a high differential pressure whenpumping a large percentage of gas. As a result, the first stage orliquid ring compressor portion of the pump, was required to spanessentially the complete pressure range between the inlet and outlet ofthe pump. In cases where the desired delivery pressure of the prior artpump might be equal to the maximum ability of the first stage liquidring impeller, or even beyond its pressure differential producingability, the pump might become inoperative when a large quantity of airor gas was handled.

However, when a pump according to my prior patent was required to handleall liquid, the unit would readily span the required differentialpressure range, because the second stage centrifugal pump portion wasnot required to pump a high volume of gas and was accordingly able tooperate efficiently over a large pressure differential range, thusleaving very little pressure difference for the first stage liquid ringimpeller to produce.

According to the present invention, some of the aforesaid operationalcharacteristics of a pump according to my prior invention are avoided byproviding for the inter-stage discharge of separated gases so that noneed for their passage through the centrifugal impeller portion isrequired. The interstage removal of gases and non-condensable vaporspermits the liquid impeller portion of the pump to operate at its fullcapacity or efficiency as Well as permits the liquid ring compressorportion to operate over its designed compression ratio range. By thusremoving the air or gas from an inter-stage point within the pump andthereby leaving the eye of the impeller free of gas, the impeller Willhandle only liquid with the result that the overall density within theimpeller passageways is kept to a value approaching that of liquid onlyand thus the impeller is capable of creating a greater pressuredifferential between its eye and its discharge than it could maintain ifit had to operate in the environment of the prior art.

By thus increasing the pressure differential producing ability of thissecond stage liquid impeller, it takes over a large proportion of thetotal pressure difference required of the pump in its applicationbetween its inlet and discharge, and thus reduces the pressuredifference CII 3,213,794 Patented Oct. 26, 1965 ICC requirement of therst stage liquid ring pump portion. This relationship, therefore,automatically balances the load between the first and second stagesallowing the compressed gas to be discharged at a lower intermediatepressure, which is more commensurate with the capability of the firststage liquid ring pump and allows the second stage centrifugal impellerto handle its designed liquid quantities over its designed pressurerange.

Accordingly, a principal object of the present invention is to providefor the interstage discharge of gases and non-condensable vapors in apump of the type described and thereby provide full second stageperformance by the liquid impeller portion while at the same timereducing the pressure differential over which the first stage liquidcompressor portion must operate.

This principal object is accomplished by the provision of a novelvapor-liquid separator construction employing a plurality of inclinedpassageways strategically placed through a central portion of the liquidimpeller wall. These passageways function to centripetally separate thegas and vapors near the eye of the impeller. Vapor and liquid separationis further enhanced in the novel construction by a second plurality lofpassageways, located radially outward from the first passageways, whichcommunicate through a Wall of the impeller with an annular sealingchamber to drain any liquid therefrom back to the working side of theimpeller and thereby prevent flow of said liquid into the vapor and gasdischarge portion of the pump.

In addition, the present invention employs a novel structuralarrangement of the various elements thereof to present improvedoperating eiiciency over the structural arrangement of applicantsaforementioned patent. The novel structural arrangement employs acombined impeller-compressor rotor driven by a shaft extending from theimpeller side of the rotor to a suitable motor means. This arrangementpermits maximum area inlet and outlet port cylinder passages fordirecting inlet liquid and vapor into and away from the liquid ringcompressor portion on the pump, because the port cylinder need not beobstructed with the passage therethrough of the rotor drive shaft inview of its previously mentioned connection of the shaft to the impellerside of the rotor. This structural arrangement is a considerableimprovement over applicants prior art structural arrangement in hisaforementioned issued patent in that increased area inlet and outletpassages are permitted within the port cylinder for delivery of fluid tothe liquid ring pump.

Another object of the invention is to provide interstage discharge ofseparated gases so that improved operating conditions for both the firststage compressor and the second stage liquid impeller result whenhandling combinations of liquids and gases.

Accordingly, an object of the invention is to provide a pump includingimproved means for separating the discharge liquids from the dischargedvapors and gases.

Yet another object of the invention is to provide an improvedcentrifugal impeller construction having means for separating vapor andgases from the liquid being pumped thereby.

Yet another important feature of the invention is to provide an improvedimpeller construction incorporating a plurality of aperturestherethrough, strategically located with respect to the blades upon saidimpeller,

so that improved liquid and vapor separation is accomplished.

Yet another object of the invention is to provide a novel structuralarrangement for a pump including a lobed liquid ring vapor compressionportion and a certifugal impeller portion connected in seriesarrangement for pumping fluids in both a liquid and a vapor or gas stateor any combination thereof.

Yet another object of the invention is to provide an improved pump ofthe character described wherein the lobed liquid ring vapor compressionportion thereof is provided with a central port cylinder which isunobstructed by the rotor drive shaft and includes inlet passagesextending therein on one side thereof and outlet passages extendingtherefrom on the opposite side thereof.

Another object of the invention is to provide a pump for two-phasemixtures having large straight-through passageways in the central portcylinder unrestricted by passage therethrough of the rotor-impellerdrive shaft.

These Yand other objects and advantages of the invention will becomeapparent and the invention will be fully understood from the followingdescription and drawings, in which:

FIG. 1 is a vertical cross-section of a pump embodying the invention;

FIG. 2 is a cross-sectional View taken along line 2-2 of FIG. l;

FIG. 3 is a cross-sectional view taken along line 3 3 of FIG. l; and

FIG. 4 is a cross-sectional view taken along line 4 4 of FIG. 1.

Referring to the drawings in general, and FIG. 1 in particular, thenovel pump structure includes a main housing having a volute portion 10,a central lobe portion 12 and an end inlet head portion 14, each ofwhich are rigidly attached to yone another by securing means, such asbolts (not shown). Affixed to the inner face of the head portion 14 is astationary cylindrical port cyllinder 16, which projects inwardlytherefrom into a central portion of an impeller-rotor, shown generallyat 18. The impeller-rotor 18 is affixed by a nut 22 to the end `of adrive shaft 20 which may be connected to any suitable drive means, suchas a motor (not shown). Secured to an inside portion of the volutecasting is an annular seal plate 24 which encloses a double typeresilient shaft seal 26, of conventional design, in closeleak-preventing contact with the drive shaft extending therethrough.

The foregoing general description is intended merely to afford anover-all comprehension of the basic structural arrangement of applicantsnovel pump as a prelude to the detailed description of the illustrativestructure which follows.

The inlet head portion 14 includes an inlet opening 28 about which aflange 30 extends to all connection therewith of, for instance, asimilarly flanged inlet conduit. The inlet 28 communicates with a pairof bifurcated inlet ports 32 formed in the port cylinder 16, whichextend radially outward to form inlet passageways to the innerperipheral portion of a plurality of blades 36 formed in theimpeller-rotor 18. The blades 36 divide the liquid ring compressorportion of the rotor 18 into a plurality of vapor pumping chambers 34(FIG. 3). The central lobe portion 12 of the pump housing surrounds thebladed portion of the impellerrotor and includes a pair of opposed lobes38 separated by intermediate land portions 39. Connected to the headportion 14 is a conduit 44 for introduction of seal liquid into thelobed portion of the pump housing through one or more orifices 46 in aflange portion of the port cylinder 16.

As is Well understood by those skilled in the art, the blades 36 dividethe rotor into a series of pockets or chambers 34, which are ope-n attheir inner and outer ends. As a particular chamber 34 traverses theextending part of a lobe 38 in the direction of rotation indicated onthe drawings, it discharges a portion of seal liquid into thecrescent-shaped lobe 38 between the rotor periphery and the housing 12,causing gas and vapor to be sucked into the inner end of the chamber 34through the inlet 28 and inlet ports 32. As each of the chambers 34continues to rotate and traverse the decreasing radius part of the lobe38, liquid from the lobe is forced back into the chamber 34 causing thechamber to become substantially full of liquid once more. This alternaterecession of the liquid in each of the chambers and thereafter advanceof the liquid back into the chambers during the rotation thereofcompresses the gas and vapor therein and causes it to be expelled incompressed form out through a pair of discharge ports 40 on the oppositeside of the port cylinder 16 i-nto the central eye area 42 of aplurality of centrifugal impeller blades 48. Each of the impeller blades48 extends between an outside wall 50 and a wall portion 52 dividing theimpeller portion of the impeller-rotor 18 from the rotor portion of themember. Liquid entering the inlet eye 42 of the impeller iscentrifugally forced radially outward between the spirally-shapedimpeller blades 48, through exit slots 54, into volute discharge chamber76 and outwardly through liquid discharge opening connected to anysuitable discharge conduit by a discharge flange 78.

The novel centrifugal separating aspect of the present invention isaccomplished by providing a plurality of inclined passageways 56 throughthe outside wall portion 5i) of the impeller. The passageways 56 areinclined to the axis of rotation of the impeller and strategicallyplaced so as to pick-off the centripetally separ-ate gas and vapor nearthe eye of the impeller.

An important feature of the invention is the positioning of theapertures 56 in the angular relationship shown. It will be noted thatpassageways 56 are positioned so that the fluid flowing in from theblade side of the outside wall 50 is directed radially inward. Bydirecting the ow inwardly, and thus against centrifugal force, there isa further centrifugal separating effect within the passageways 56 whichseparates out any residual liquid droplets. Bec-ause of the angularinclination of the passageways 56, thus described, the separated liquidis redirected along the outer radial surfaces of these holes back intothe impeller blade pumping section. There is thus developed a somewhatcircular flow pattern through the passageways 56 due to this centrifugaleffect, with the gas being discharged at the inner radius of thepassageways 56 into an annular intermediate collection chamber 58, withthe liquid being discharged in counter flow back into the bladed sectionof the impeller.

The separated gas and vapor collecting in the charnber 58 is dischargedoutwardly through a plurality of arcuate openings 60 (FIGS. 1 and 4)formed in the seal plate 24 into an enlarged vapor discharge chamber 62within the volute portion 10, `and thereafter outwardly through a vapordischarge conduit 64. The discharge chamber 62 includes a threaded plug66 at its lower portion whose position obviously may be interchangedwith the threaded discharge conduit 64 to give an alternate vapordischarge connection. Plug 66 is also readily removable to allowdrainage of any accumulated condensate in the chamber 62.

The impeller portion of applicants novel pump is further provided withnovel liquid seal means on the outside of the wall portions 50 and 52.Outside wall Si) carries concentric inner and outer raised sealingrings, respectively 68 and 70, which protrude outwardly into acorresponding U-shaped annular groove 72 formed in the seal plate 24.The concentric seal rings 68 and 70 form `a U-shaped annular trough 71therebetween which is vented through apertures 74 to the liquid pumpingside of the impeller and thereby prevent flow of higher pressure liquidin chamber 76 into the lower pressure air chamber. The outermost annularring 7 0 acts as a first defense in holding back the liquid within thechamber 76, and such liquid that may leak by the first sealing ring 70is collected in the annular space 71 and is permitted to escapetherefrom through the apertures 74 back to the working side of theimpeller.

A very important aspect of applicants interstage discharge of gases andnon-condensable vapors is the strategic placement of the apertures 56and 74 within the impeller with respect to the blades 48 locatedthereon. Aptertures 56 are purposely placed, by suitable rotationalindexing in the manufacturing process, to be adjacent the trailing edgeof their respective impeller blades 48. The action of the leading edgeof the impeller picks up the liquid, exerting pressure on the liquid andcausing it to rotate and develop centrifugal force as it passes throughthe blade passageways 50. On the opposite or following edge of theimpeller blade, a suction or lower pressure is normally developed and itis in this backwater Y region or low pressure area that the opening 56is placed to withdraw air and non-condensable gases which naturallyaccumulate and are forced to this low pressure area by the centrifugaland other forces exerted on the air, all of which direct suchaccumulation to this backwater region. It should be also noted that eachof apertures 56 is placed radially with respect to the impeller at assmall a radius as possible and yet be at the same time placed behind theentering blade.

Similarly, apertures 74 are also strategically placed relative to thetrailing edge of their respective impeller blades 48 (see FIG. 2)although at a larger radius than the apertures 56, to be in the bestposition to withdraw the accumulation of liquid leakage from trough 71.The placing of apertures 74 next to the backside of the impeller blades48 is to obtain the minimum pressure within the impeller at this radiusso as to obtain the maximum pressure difference between the trough 71and the impeller passageways Si), to facilitate the return of liquidaccumulated within the trough 71.

The wall portion 52 shrouding the opposite sides of the impeller blades48 is ladapted to rotate in close relation to an adjacent wall portionof the lobe housing 12. The outside portion of the wall 52 carries aprojecting annular seal ring 8i) which rotates within a U-shaped groove82 in the lobe portion 12. The complementary relationship of theU-groove 82 with the annular ring 80 provides an effective seal forlimiting any leakage of relatively higher pressure liquid in the volute76 back toward the lobe portion 38 to effectively isolate the respectiveportions of the pump.

However, to prevent excess leakage of liquid or gas between chamber 76to the lobe displacement chamber 38 when a pressure differential existstherebetween, additional apertures 84 are provided which connect achamber 86 to the interior passageway Sil of the impeller. The apertures84 enter into the impeller passageways 50 at a smaller radius than theoutside diameter of the impeller, and therefore into a lower pressurearea than the volute chamber 76 as well as lower than the pressureexisting in the chamber 86. The apertures 84, in addition to relievingthe excess pressure built up in the chamber 86 to the lower pressurearea of the impeller, are placed on the trailing or back edge of theimpeller blade 48 to take advantage of the still lower pressure existingin this trailing face area in a manner similar in principle to theaforementioned strategic placement of apertures 56 and 74.

Thus, it can be seen how applicants arrangement has provided for a novelcentrifugal vapor and gas separator means for a pump having the capacityto pump liquids, gases and vapors. The centrifugal separating meansemploys a plurality of inclined passageways which effectively bleedcompressed vapor from the inner portions of the impeller pumpingchambers without loss of liquid therethrough. The impeller portion ofthe invention also includes a novel liquid seal means employing a pairof concentric grooves on an outer Wall of the impeller wherein theannular trough-like space between the rings is vented to permit returnof any leakage thereto back to the working side of the impeller.Furthermore, the invention has provided a novel multiphase pumparrangement wherein the central port cylinder 16 is not interrupted bythe passage of the rotor drive shaft therethrough, thereby enlarging theinlet and discharge ports to yield increased pumping efficiency due tolower frictional losses.

While the invention is disclosed as embodying a cylindrical inlet port16, it will be readily apparent to those skilled in the art that thesaid port could be modied to a conical shape, according to the teachingsof applicants prior art Patent No. 2,713,968, without departing from thescope of the present invention. Those skilled in the art will alsorealize that the impeller portion of the present rotor need notnecessarily be of the shrouded vane type to employ applicants novelpassageways 56 and 74 and seal rings 68 and 72. Additionally, thoseskilled in the art will readily appreciate the novel arrangement ofstrategically placed apertures through a wall portion of the impeller,is equally applicable to the liquid and vapor centrifugal separator art,as well as to the multiphase pump art, and applicant has only describedhis invention in combination with this particular pump art for purposesof illustration.

While a specific embodiment of the invention has been shown anddescribed in detail to illustrate the application of the inventiveprinciples, it will be understood that the invention may be embodiedotherwise without departing from such principles.

What is claimed is:

1. In series pumping combination, a rst stage liquid ring vaporcompression pump and a second stage centrifugal impeller liquid pump,said liquid pump including a volute housing, an impeller having aplurality of pumping chambers rotatably mounted in said housing, andmeans for centrifugally separating vapor from the liquid being pumped bysaid impeller, said last mentioned means comprising a plurality ofpassageways in said impeller extending through a wall thereof to vent aninner radial portion of each of said chambers to an outside wall portionof said impeller, and chamber means formed in said volute housing toreceive the separated vapor from said passageways, said first stageliquid ring vapor compression pump being sized and proportioned to pumpits full displacement volume of intake vapors and gases over the pumpsdesigned pressure range and discharge its compressed vapors and gases tosaid second stage centrifugal impeller liquid pump, said impeller liquidpump being sized and proportioned relative to said liquid ring vaporcompression pump to pump substantially all liquid over the same designedpressure range.

2. Apparatus according to claim 1, wherein an outside wall of saidimpeller includes sealing means having a pair of spaced concentricannular ribs which project into a U-shaped annular trough portion ofsaid volute housing to inhibit ow of liquid at the periphery of theimpeller toward the impeller axis of rotation, and at least one aperturethrough the impeller wall between said ribs to permit drainage of anyliquid collected therebetween back to the impeller chambers.

3. A vapor and liquid pump comprising a housing having a volute portionand an adjacent lobed portion formed therein, a rotor rotatably mountedwithin said housing, said rotor including a bladed first stage portionadapted to circulate a ring of seal liquid in said lobed portion, and acentrifugal impeller second stage portion adapted to rotate in saidvolute portion and receive the entire vapor and liquid discharge fromsaid lobed portion, said infpeller second stage portion including awall, radially extending blades upon said wall defining centrifugalpumping channels therebetween, and a plurality of passageways extendingthrough said wall to place an inner radial portion of each of saidchannels in communication with the outside surface of said wall, andchamber means in said housing to receive and separately discharge thevapor flowing in said passageways from the liquid owing centrifugally insaid channels, said first stage portion being sized and proportioned topump its full displacement volume of intake vapor over the pumpsdesigned pressure range and discharge the compressed vapor to saidsecond stage portion, said second stage portion being sized andproportioned relative to said rst stage portion to pump substantiallyall liquid over the same designed pressure range, said passageways beinginclined to the axis of rotation of said impeller portion in a directionradially outward toward the wall of said impeller second stage portioncarrying said blades.

4. A vapor and liquid pump according to claim 3, wherein the outersurface of said impeller portion Wall includes seal means comprising apair of spaced concentric sealing ribs formed thereon for inhibitingflow of higher pressure liquid from said volute portion into saidchamber means.

5. A vapor and liquid pump according to claim 4, including in addition,at least one passageway through said impeller wall to place the spacebetween said annular ribs in communication with said channels.

6. A pump according to claim Where said last mentioned passageway ventsthe space between the annular ribs with a relatively low pressure areaadjacent the inner portion of said impeller blades.

7. A multi-purpose pump for operation either as a vapor and gascompressor or as a liquid pump exclusively for pumping combinationsthereof comprising a housing having a volute portion and an adjacentlobed portion formed therein, a rotor rotatably mounted within saidhousing, said rotor including a bladed annular first portion adapted tocirculate a ring of seal liquid in said lobed portion, and an impellersecond portion adapted to rotate in said volute portion and receive thedischarge from said lobed portion, said second portion including aplurality of impeller blades secured to an end Wall of said firstportion, a circular end wall enclosing said impeller blades to form aclosed face type liquid impeller, a plurality of passageways extendingthrough said circular end wall for separating compressed vapor from theinlet of said impeller, said passageways being located about andadjacent the axis of rotation of said rotor and being inclined to saidaxis of rotation in a direction so that the inner end of each of saidpassageways is at a greater radial distance from the rotor axis ofrotation than the outside ends of said passageways, seal meanscooperative between the end wall of said impeller and an adjacentportion of said housing, said seal means including a pair of raisedconcentric annular rings and at least one aperture therebetweenextending through the impeller end wall, said rings being at a greaterradial distance from said rotor axis of rotation than said pasageways,inlet port means secured to one end of said housing extending axiallywithin a central portion of said rotor rst portion for conducting gasesand liquids to said lobed portion, a rotor drive shaft extending throughthe opposite end of said housing secured to the impeller end wall, vaporand gas collection chamber means in communication with the outer endportions of said pasageways, and liquid discharge means connected tosaid volute portion for conducting liquid therefrom, said lobed portionand cooperative rotor rst portion being sized and proportioned to pumpits full displacement volume of intake vapors and gases over said pumpsdesigned pressure range and discharge said compressed vapors and gassesto said volute portion and cooperative rotor second portion, said secondportion being sized and proportioned relative to said rst portion topump substantially all liquid over the same designed pressure range.

References Cited by the Examiner UNITED STATES PATENTS 1,797,810 3/31Vogel 103-112 1,901,154 3/33 Durdin 103-5 1,946,212 2/34 Jacobsen103-113 l 1,986,706 1/35 Beyer 103-111 2,758,815 8/56 Fontaine et al103-113 2,761,393 9/56 De Stefano et al. l 103-113 2,940,657 `6/60 Adams230-79 FOREIGN PATENTS 404,281 10/ 24 Germany.

462,232 7/ 28 Germany.

838,859 5/52 Germany.

KARL I. ALBRECHT, Primary Examiner.

JOSEPH H. BRANSON, JR., Examiner.

1. IN SERIES PUMPING COMBINATION, A FIRST STATE LIQUID RING VAPORCOMPRESSION PUMP AND A SECOND STAGE CENTRIFUGAL IMPELLER LIQUID PUMP,SAID LIQUID PUMP INCLUDING A VOLUTE HOUSING, AN IMPELLER HAVING APLURALITY OF PUMPING CHAMBERS ROTATABLY MOUNTED IN SAID HOUSING, ANDMEANS FOR CENTRIFUGALLY SEPARATING VAPOR FROM THE LIQUID BEING PUMPED BYSAID IMPELLER, SAID LAST MENTIONED MEANS COMPRISING A PLURALITY OFPASSAGEWAYS IN SAID IMPELLER EXTENDING THROUGH A WALL THEREOF TO VENT ANINNER RADIAL PORTION OF EACH OF SAID CHAMBERS TO AN OUTSIDE WALL PORTIONOF SAID IMPELLER, AND CHAMBER MEANS FORMED IN SAID VOLUTE HOUSING TORECEIVE THE SEPARATED VAPOR FROM SAID PASSAGEWAYS, SAID FIRST STAGELIQUID RING VAPOR FROM SAID PUMP BEING SIZED AND PROPORTIONED TO PUMPITS FULL DISPLACEMENT VOLUME OF INTAKE VAPORS AND GASES OVER THE PUMP''SDESIGNED PRESSURE RANGE AND DISCHARGE ITS COMPRESSED VAPORS AND GASES TOSAID SECOND STAGE CENTRIFUGAL IMPELLER LIQUID PUMP, SAID IMPELLER LIQUIDPUMP BEING SIZED AND PROPORTIONED RELATIVE TO SAID LIQUID RING VAPORCOMPRESSION PUMP TO PUMP SUBSTANTIALLY ALL LIQUID OVER THE SAME DESIGNEDPRESSURE RANGE.